Lung cancer is the cancer with the largest mortality in Belgium. Nowadays, the most potent risk factor for lung cancer, tobacco smoking, is increasing, principally in teenagers. It is therefore necessary to intervene more efficiently in the natural history of the disease. This aim can be achieve by the early detection and the local treatment of small size lung cancer and in situ carcinoma. Interestingly, pulmonary preneoplastic lung lesions have been identified and characterized in the central airways as well as in the peripheral lung parenchyma. These preneoplastic lesions can evolve to invasive cancer or regress after tobacco smoking cessation or chemoprevention treatment. A new autofluorescence based endoscopy technique is described, that allows to detect preneoplastic pulmonary lesions and radio-occult lung cancer. These small sized lesions can be cured with endoscopic local treatment such as photodynamic therapy.